Led causing popping?

[ch1naski]

Hey all. I've got a phaser that pops when I switch it on. I've wired it so input is grounded, and even went beyond that and threw a 1 meg pulldown from board input to ground. But the popping persists. Before I try soothe pdr on the output, is there another way to stop the popping if it's due to the led?

Thanks fellas

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[das234]

+1 on this question.  I've tried everything I could find on my Sea Urchin and it still pops.

[davent]

Haven't had to deal with this [edit(yet)] but info here.

http://www.muzique.com/lab/led.htm

dave

[ch1naski]

great help, davent. thanks.

[jimilee]

Well that's awesome, a little piece of vero should do the trick. My delays are the only ones that pop for me. Usually during set up, I'll switch them on and off a couple of times, usually does it.

[ch1naski]

This tidbit of the cap and resistor on the LED did drastically reduce the popping, it's just that slight mechanical pop now. Annoying, but doable.

Thanks for steering me to the right place, davent. I knew I could count on the good folk here.

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[das234]

Well that's awesome, a little piece of vero should do the trick. My delays are the only ones that pop for me. Usually during set up, I'll switch them on and off a couple of times, usually does it.

If you try this on one of your popping delays, Jimi, let me know how it works.  If I get around to it first, I'll do the same.

[Thomas_H]

This is an interesting topic as I am having problems in understanding the issue.

If it is true that a LED is able to cause an audible pop then its because the current drawn when powering it up causes side effects on the power rail of the pedal.
If we are talking about a standard LED I can follow the argument that the current (approx 20mA) can cause a popp signal in an effect with a poor power supply design.
If we are looking at a super / ultrabright LED which uses CLRs of approx 10k, the resulting current would be 0.9mA. If this still causes a Popp - I strongly suggest to have a look at the power supply design of the effect in a whole.

So the easiest solution would be to use a CLR of 10k and replace the existing LED with a super/ultrabright one.
Would someone with that problem try this as it is far easier than adding a veroboard? I am really interested in the solution to this problem.

[ch1naski]

This is an interesting topic as I am having problems in understanding the issue.

If it is true that a LED is able to cause an audible pop then its because the current drawn when powering it up causes side effects on the power rail of the pedal.
If we are talking about a standard LED I can follow the argument that the current (approx 20mA) can cause a popp signal in an effect with a poor power supply design.
If we are looking at a super / ultrabright LED which uses CLRs of approx 10k, the resulting current would be 0.9mA. If this still causes a Popp - I strongly suggest to have a look at the power supply design of the effect in a whole.

So the easiest solution would be to use a CLR of 10k and replace the existing LED with a super/ultrabright one.
Would someone with that problem try this as it is far easier than  adding a veroboard? I am really interested in the solution to this problem.

My situation was slightly different than most, as I have the led connected to the LFO on a phaser, so that it blinks with the rate.

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[Thomas_H]

My situation was slightly different than most, as I have the led connected to the LFO on a phaser, so that it blinks with the rate.

I see your point but how is that different? Is the LED part of a LED/LDR combination?
It can be replaced for a superbright as well, cant it ?

[ch1naski]

It's just an indicator led, not any part of the functional signal path. So it could be replaced. I believe it's a superbright, I don't remember now. But it's very bright, considering that I  have a 5.1k clr on it.  I've already done the res/cap to ground mod in it, which reduced the pop considerably, but there is a small pop left. I was assuming it was the pitfall of using mediocre 3pdt footswitches.

I may go back in and throw a 10k in there and see if I get close to silent switching.

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[Thomas_H]

I may go back in and throw a 10k in there and see if I get close to silent switching.

I sometimes use up to 22k and its still bright :-)

[ch1naski]

I suppose that I could leave the cap connected and tie in a larger resistor. I don't look forward to pulling the board out again.

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[jimilee]

What phaser are you building? I've never seen this issue on a phaser which leads me to believe that there is a phaser I haven't seen.

[ch1naski]

What phaser are you building? I've never seen this issue on a phaser which leads me to believe that there is a phaser I haven't seen.

Lol, jimi
It's a Galacticon. With the led connected up to the LFO

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